It is known that cushioning materials are produced by integrally bonding a paper or rigid resin plate and a vacuum molded article of a resin sheet. Japanese Patent Publication No. 47335/83 and U.S. Pat. No. 3,674,109 disclose a method for producing a container with a cover or a cushioning material which comprises superimposing an air-impermeable sheet made of a thermoplastic resin and a paper having microholes and with a synthetic resin film laminated thereon or rigid resin plate which comprises bringing the air-impermeable sheet into contact with a mold, heating the assembly at a temperature higher than the heat distortion temperature of the air-impermeable sheet, and then vacuum molding only the air-impermeable sheet along the mold.
In producing a box using the cushioning material produced by the above vacuum molding method, however, the paper with printing applied thereon appears outside and the microholes of the paper give a singular feeling to the consumer.